Production of monoalkyl aromatic hydrocarbons



May 5, 1953 F. M. SMITH ET AL PRODUCTION OF MONOALKYL AROMATIC HYDROCARBONS Filed July 14, 1949 ruw INVENTORS E M. SMITH RS. HANMER WWMAAMMW A TTORNEYS Patented May 5, 1953 PRODUCTION OF MONOALKYL AROMATIC HYDRO CARBON S Fredrick M. Smith, Bartlesville, Okla., and Robert S. Hanmer, Berger, Tex., assignors to Phillips Petroleum Company, a corporation of Delaware Application July 14, 1949, Serial No. 104,634

5 Claims.

This invention relates to the alkylation of hydrocarbons. In on of its aspects the invention relates to the alkylation of an aromatic hydrocarbon, for example a monocyclic aromatic hydrocarbon. In another aspect the invention relates to the alkylation of an aromatic hydrocarbon to produce a monoalkyl aromatic hydrocarbon. In still another of its aspects the invention is of a process for the production of a high molecular weight monoalkyl aromatic hydrocarbon. In a further aspect, the invention relates to alkylation of an aromatic hydrocarbon with a high molecular weight olefin from an olefinic fraction containing the same to obtain a product which comprises essentially monoalkyl aromatics free from contaminating polyalkyl aromatics boiling in the same range. In a still further aspect the invention relates to a process for the production of a product consisting of high molecular weight monoalkyl aromatic hydrocarbons by the alkyladitions to separately alkylate an aromatic hydrocarbon; the alizylates can be fractionated separately and a product then made up to have any desired molecular weight distribution, or the alkylate blended directly to produce said product, as will appear more fully below.

The alkylation of aromatic hydrocarbons with high molecular weight polymer olefins in the presence of Friedel-Crafts catalyst including those of the liquid type such as hydrogen fluoride is well known in the art. Similar alkylations have been disclosed wherein the olefin alkylating agents ar of the non-polymeric type obtained from such sources as the cracking of topped crudes, high boiling naphthas or as oils, and the like. In such processes the olefin feed stock is usually supplied in the form of a concentrate comprising, in addition to the olefins, greater or less amounts of parafiins, naphthenes, and aromatic materials boiling in the same range. The alkylates obtained from such operations have numerous uses among which one principal application lies in their employment as intermediates in the production of detergents. Monoalkyl benzenes for use in the manufacture of detergents are generally those in which olefins containing from ten to fifteen carbon atoms to the molecule are used as alkylating agents. In the production of such alkylates, the olefinic fractions employed in processes heretofore disclosed comprise cuts boiling in the range 300 to 500 F. in order to include olefins of the aforementioned carbon content.

Although the boiling range of the particular olefin concentrat may be adjusted as desired, the molecular weight distribution of the olefins constituent in the fraction so obtained is necessarily fixed by the source of the said concentrate and/or by the process employed in its production. For example, olefin concentrates obtained from. the polymerization of, say, propylene or butylene will have a molecular weight distribution substantially different from concentrates boiling in the same range but obtained from fractionation of a cracked heavy naphtha or gas oil, this'property being characteristic for each concentrate. Obviously alkylates produced using these different olefin concentrates as the alkylating agent will vary correspondingly in composition. The detergent characteristics of alkyl aromatic sulfonates are influenced to a considerable extent by the chain length of the substituent alkyl group and/or the molecular weight distribution. Thus it is obvious that heretofore the characteristics of alkyl aromatic sulfonate detergents have been greatly influenced by the origin and subsequent treatment of the particular olefin alkylating stocks used in the manufacture of the alkyl aromatic intermediates employed in their production. It is also obvious that to produce alkyl aromatic sulfonate detergents of uniform and reproducible characteristics, the, alkylate sulfonation stock has had to be produced heretofore from olefins having a specific origin.

A further disadvantage of procedures heretofore employed lies in the fact' that it is substantially'impossible to isolate an alkylate product comprising essentially monoalkaryl hydrocarbons, regardless of the particular source of the olefin alkylating stock employed. As previously pointed out, the olefin alkylating agents are usually concentrates boiling within a relatively broad range. Lighter olefins constituent in the said concentrates condense with the aromatic material used, to form polyalkylate boiling in the same range as monoalkylate produced from the higher molecular weight olefins contained therein. Yet to provide the necessary molecular weight distribution for general purpose detergent intermediates, as well as for obvious economic reasons,

olefin concentrates having a wide boiling range;

3 often from about 100 to 200 Fahrenheit degrees are required.

This invention provides a process for the production of high molecular weight monoalkyl aromatic hydrocarbons having any desired molecular weight distribution, using olefin concentrates from any available source without restriction as to the molecular weight distribution in the said concentrates. According to the process of our invention, a suitable aromatic hydrocarbon is alkylated in concurrently operating parallel steps, the alkylating agent employed in the said parallel steps comprising desirable narrow boiling fractions of the particular olefin concentrate selected.

The olefin concentrate employed maybe tromiany available source and may comprise polymericolefins such as are produced by the catalytically activated polymerization of light olefins or nonpolymeric olefins of the type produced from cracking high boiling naphthas or gas oils. The concentrate employed, usually having a boiling range of about 190 F.-200 F. with a minimum boiling point of at least 300F. and a maximum boiling point of not more than 500 F., is first fractionated into several narrow boiling cuts. These cuts are then introduced into the several parallel aikylation zones where they serve as alkylating agents for the aromatic hydrocarbon portions distributed thereto. The efliuent streams from the alkylators are individually fractionated to produce essentially monoalkyl and polyalkvl aromatic hydrocarbons, thus providing a series of alkyla-tes having individual characteristics instead of the single broad-boiling-range product containing not only monoalkylate of overlapping molecular weights but also appreciable amounts of polyalkylate .boiling within the same range. The monoalkylate streams from the several steps are finally combined either in their totality or,

when preferred, in any proportion, thus providing a final monoalk-ylate product having any desired molecular weight distribution, the said product being essentially free from undesirable polyalkylates.

It is an advantage of our process that the production of monoalkyl aromatics having controlled molecular weight distributions is effected virtually without regard to the particular origin and/or nature of the olefin concentrate used in their manufacture. This feature of our invention is of great practical significance since the production of alkyl aromatics is dependent upon a continuous supply of olefin alkylating stocks and such supplies may fluctuate frequently because of marketing or manufacturing variations, lien.- dering it necessary or economically desirable to utilize stocks from varying sources. Another advantage of our process lies in the production of allrylates of fixed or readily controlled characteristics to supply the rather exacting demands of synthetic detergent manufacturing. A further advantage of our process lies in the essentially complete freedom from polyalkyl aromatic constituents in the product, a feature having considerable significance when the product is employed as a detergent intermediate.

A still further advantage of our invention lies in the improved overall yields which are possible from a given olefin concentrate. When the alliyl tion is carried out according to procedures heretofore used, a certain yield of useful alkylate Will be obtained. We have discovered by the present process that under the usual conditions, higher yields are obtained from those steps wherein the alkylating fraction is of lower molecular weight, that is from the lower boiling portion of the total concentrates and lower yields are realized from those steps wherein the higher molecular weight fractions are employed. Thus, when employing the same conditions in all steps, the average yield is about the same as that obtained when the total concentrate is employed in aisingle step or zone as the alkylating agent. W e have found, however, that by suitable adjustment of conditions in each of the parallel steps of our process, maximum yields can be obtained from each of the said steps, thus providing a considerably increased overall yield. For example, in

those steps in-which the higher molecular weight fractions are used, less drastic conditions than are employed for the relatively lower molecular weight portions, that is, lower acid strength and/or lower operating temperature, are employed, thus reducing the degree of splitting of these more fra ile compounds.

Theseand other advantages are apparent from a consideration of the fiow diagram and the following description of an embodiment of the invention making reference to said diagram. The specific feed stocks and conditions which are mentioned are illustrative of the invention.

Now referring to the flow diagram, an olefin concentrate, such as that obtained in the cracking of petroleum naphthas or by the polymerizetion .of propylene or the like, having a boiling range of 350 to 450 F. is passed via line I into fractionator 2. This olefin concentrate is fractionated therein into four cuts having boiling ranges of 350 to 375 F., 375-.400 F., NT-425 R, and 4Z5-450 R, which cuts are conveyed to the four reactors via lines 3, v4, .5, and .5, respectively. Benzene drawn from storage 1 via line 8 or from recycle lines 24, 24a, 24b and 240 is mixed with each olefin stream in proportions which give the desired mol ratio of benzene to olefin. Since the reactors are identical in regard to the fiow of the various streams, only one need be described in detail. It is understood, however, that reaction conditions in each reactor may be adjusted separately to give maximum yields of useful alkylate from the particular narrow-boiling range olefin fraction charged in each case. The catalyst, comprising per cent anhydrous hydrogen fluoride and 10 per cent catalyst soluble oil, enters the reactor via line 2], hydrocarbon feed and catalyst entering the reactor in the ratio of 1 part catalyst to 3 parts hydrocarbon. The total reaction mixture-isagitated for a period of 30 minutes at a temperature of F. after which the effluent passes via line l0 into separator I 1. In the separator the catalyst phase separates from the hydrocarbon phase by gravity and is withdrawn through line 12. A minor portion of the catalyst is passed via line 43 to regeneration unit 55 where catalyst soluble oil is recovered and removed from the system via line [6. Regenerated hydrogen fluoride is returned via lines I! and 2a to the catalyst recycle stream in line l4, together with make-up hydrogen fluoride from storage [8 via line 19. The fiow rates in streams l3, l4 and 20 areadjusted to give the proper catalyst composi tion in line 21 leading into the reactor. The hydrocarbon layer from the separator l i passes into the fractionator 23 via line 22. Unreacted excess benzene is removed. overhead and returned to the reactor feed stream :2 through line 24. Deolefinized naphtha is removed from the fractionator via line :25 and may be returned to the refinery via line '26 together with corresponding fractions from the other reactors, or this material may be accumulated for specialty uses such as solvents, kerosene or the like. Light alkylate consisting principally of monoalkyl aromatic hydrocarbons is returned through line 21 to surge tanks 21a. Similar monoalkyl aromatic hydrocarbons are discharged from the fractionators to surge tanks 29a, 30a, and 3 a, respectively. From the surge tanks controlled amounts of each alkylate are passed to blender 32 where the final product alkylate is finally made up according to thedesired specifications. Heavy alkylate comprising polyalkylaromatic hydrocarbons is led via line 28 to storage 28a and in like fashion for the other stages, via lines 34, 35 and 36, respectively, into tanks 34a, 35a and 36a, respectively. These materials may be mixed in blender 31 for disposal via line 38 as specialty products.

t is apparent from the nature of the process that a blocked-out type of operation may be employed in which one reactor system operates for set periods with each of the prepared olefin fractions. By this means conventional equipment can be adapted to our invention at a minimum of additional expense.

The alkylation step in each stage can be carried out using liquid type catalysts, for example, anhydrous hydrogen fiuoride, and hydrofluoric acid compositions with water and/or boron trifluoride. The concentration of active catalyst in these compositions will be in the range of 60 to 100 per cent, preferably 80 to 95 per cent. As mentioned previously it is often desirable to vary the catalyst strength from one alkylation stage to another in the process depending upon the specific nature of the olefin therein used.

Temperatures employed for the alkylation will be 50 to 140 F., preferably 80 to 120 F. when the foregoing catalysts are employed. The particular conditions in any event are readily determinable by mere routine test. Flow rates will be adjusted to provide residence times of to 60 minutes.

The process of our invention is adaptable to the production of alkylates from benzene, toluene, and the like, by condensation with olefins of not less than seven or more than carbon atoms to the molecule. Such olefins are conveniently supplied as concentrates from the cracking of heavy petroleum naphthas, gas oils,

and the like, or from polymerization of propylene, butylenes. and the like.

An olefin concentrate produced by the polymerization of propylene and having an overall boiling range of 350 F. to 500 F, was fractionated to yield six cuts having boiling ranges as follows: 350 F.-375 F., 375 F.-400 F., 400 F.- 425 F., 425 l t-450 F., 450 F.-4'75 F. and 475 F.-500 F. These individual feed stock fractions were thereafter employed for alkylation of henzene according to the method of our invention. Mixtures of olefin and benzene containing 8 mols benzene per mol of olefin were passed with volume per cent HF catalyst through the reactors maintained at 100 F. at a rate to provide a residence time of about 30 minutes. The effluent hydrocarbon materials, after removal of catalyst were fractionated to separate monoand polyalkylaryl products. The monoalkylaryl fractions were thereafter sulfonated individually by conventional methods.

In a second test a fraction of propylene polymer boiling in the range of 350 F.500 F. was prepared and reacted with benzene using conditions similar to those reported above. The detergent range alkylate obtained was sulfonated by conventional methods.

In all, seven detergent sulfonate products were obtained as -60 mixtures with sodium sulfate and tested by standardized methods (Am. Dyestuff Reporter, vol. XVII, No. 18, 678-683, Oct. 1928) for the washing of soiled cotton cloth. The results of these washing tests, in terms of restored whiteness (reflectance) of the cloth are given in the following table:

Soft water washing test Detergent indicated bv bailing range of olefins employed.

b 1350-425 F., 50% 425-500 F.

e 30% 2.50-425 F., 425-500 F.

The results in the tabulation indicate the improved characteristics of the special detergent blends compared with the detergent prepared from the full range olefins by the prior art method. As illustrated in the first part of the table, the individual detergents derived from narrow boiling range olefins (1-6) are generally superior to the normal product ('7) and special blends (8, 9) have increased detergency as shown in these tests.

Other conditions requiring special detergents could be satisfied in a similar manner by proper combination of products 1 through 6 either before or after sulfonation of the alkylates.

Variations and modifications are possible within the scope of the appended claims to the invention, the essence of which is that a process has been set forth according to which an olefin concentrate from any source and having any molecular weight distribution and containing even undesirable substances can be used to alkylate an aromatic under conditions peculiarly adapted to yield optimum results for each desirable fraction of olefins present in said concentrate by first fractionating said concentrate to remove the desirable olefins therefrom in form of fractions and then using said olefin fractions separately to alkylate an aromatic hydrocarbon under conditions yielding optimum results with each olefin fraction, thus increasing notably the total desirable alkylate produced, fractionating separately said individually obtained alkylate to remove undesirable polyalkylates therefrom and blending these together, as desired, or blending these together without fractionation, of one or more of them, to obtain a product of any desired molecular weight range and molecular weight distribution.

We claim:

1. The alkylation of an aromatic hydrocarbon with high molecular weight olefins to produce an alkylate product having not less than seven nor more than twenty carbon atoms to the molecule which comprises fractionating an olefin concentrate having an overall boiling range 350-500 F. into a plurality of fractions, separately alkylating said aromatic hydrocarbon with each of said fractime", separately iractionating each of the.- alkylates thus produced to form from each a fraction comprising monoalkyl aromatic hydrocarbons and a fraction comprising polyalkyl arc" matic hydrocarbons and then combining said fractionscomprising monoalkyl aromatic hydrocarbons to form a product.

2. The alkyiation of claim 1 wherein said fractions comprising polyalkyl aromatic hydrocarbons are combined to form a product.

3. The alkylation of an aromatic hydrocarbon with high molecular weight olefins contained in an olefin concentrate together with lower molecular weight olefins which comprises the step of iractionating said concentrate into narrow boiling' fractions, separately allrylating said aromatic hydrocarbon with each of said fractions, the alkylation in which higher molecular weight fractions are used being; effected under conditions which are less drastic than those employed for relatively lower molecular weight fractions, separately fraction rating each alkylate thus produced to produce essentially a monoalkyland a poly alkyl-aromatic hydrocarbon stream and then combining the resulting separate monoallryl hydrocarbon streams to form a product.

4. In the production of a sulfonated monoalkylated detergent product intermediate from an olefin concentrate, having an approximate overall boiling range of 300 to 500 F., said olefin concentrate containing desirable high molecular weight olefins having not less than 7 nor more than about carbon atoms to the molecule, the lower molecule weight olefins in said range upon alkylation of an aromatic therewith resulting in polyalkylated aromatics, distributed substantially throughout the entire range of suitable monoalkylated aromatic detergent intermediate, unsuited for the production of said sulfonated monoallrylated detergent intermediate and difdcultly if at all separable therefrom, the steps in combi nation which comprise fractionating said olefin concentrate into narrow boiling fractions, separately alkylating an aromatic hydrocarbon with each of said fractions, under conditions specifically suited to each of said fractions, generally the alkylation of the fractions containing the higher molecular weight olefins being effected under conditions which are less drastic than those employed for relatively lower molecular weight fractions, separately fractionating each alkylate thus produced to produce from each essentially a monoalkyl-aromatic hydrocarbon stream and a polyalkyl-aromatic hydrocarbon stream and then combining the resulting separate monoalkyl-arcmatic hydrocarbon streams to form an alkylated aromatic product containing substantially only compounds having at least seven carbon atoms in the single alkyl group thereof.

5. The alkylation of benzene with high molecv ular weight olcfins to produce an alkylate product having not less than about 7 nor more than about 20 carbon atoms to the molecule which comprises fractionating an olefin concentrate having an overall boiling range of 350-500 F. into 6 fractions having boiling ranges as follows: 350-375 R, 375-400" R, 400-425 R, 425-450 F., 450-475 R, and 475-590 F., separately alkylating said benzene with each of said fractions employing in each alkylation approximately 8 mols of benzene per mol of olefin in the presence of approximately 30 volume per cent HF catalyst at a temperature of about F. and at a rate to provide a residence time of about 30 minutes, separately fractionating each of the alkylates thus produced to form from each a fraction comprising monoalkyl aromatic hydrocarbons and a fraction comprising polyalkyl aromatic hydrocarbons and then combining said fractions comprising monoalkyl aromatic hydrocarbons. to form a product.

FREDRICK M, SMITH.

ROBERT S. HANMER.

l'teferencesv Cited in the file. of this patent UNITED STATES PATENTS Number Name Date 2,233,408 Flett Mar. 4, 1941 2,413,161 Zerner et al Dec. 24, 1946 2,416,022 Schulze et a1 Feb. 18, 1947 2,455,601 Morris Dec. 7, 1948 2,456,119 Friedman et a1. Dec. 14, 1948 

1. THE ALKYLATION OF AN AROMATIC HYDROCARBON WITH HIGH MOLECULAR WEIGHT OLEFINS TO PRODUCE AN ALKYLATE PRODUCT HAVING NOT LESS THAN SEVEN NOR MORE THAN TWENTY CARBON ATOMS TO THE MOLECULE WHICH COMPRISES FRACTIONATING AN OLEFIN CONCENTRATE HAVING AN OVERALL BOILING RANGE 350-500* F. INTO A PLURALITY OF FRACTIONS, SEPARATELY ALKYLATING SAID AROMATIC HYDROCARBON WITH EACH OF SAID FRACTIONS, SEPARATELY FRACTIONATING EACH OF THE ALKYLATES THUS PRODUCED TO FORM FROM EACH A FRACTION COMPRISING MOMOALKYL AROMATIC HYDROCARBONS AND A FRACTION COMPRISING POLYALKYL AROMATIC HYDROCARBONS AND THEN COMBINING SAID FRACTIONS COMPRISING MONOALKYL AROMATIC HYDROCARBONS TO FORM A PRODUCT. 